In an integrated optical system, the problem exists to conduct light from such a waveguide located on components, e.g. a photoelectric detector, or to feed light from a light source, e.g. a semiconductor laser, into a waveguide. The light must thereby exit through the end face of the waveguide end or enter into this end face.
When edges of a glass substrate are mechanically processed microscopically small fractures are produced. The exiting light is scattered through these fractures. In order to prevent the scattering, the waveguide end is polished with conventional means. This is a very expensive procedure which requires specialized personnel.
In many cases it is desired to couple a waveguide inside an integrated optical system with components. To this end, small grooves can be milled in the substrate by means of a diamond impregnated disk milling cutter. The side walls of these grooves also form roughly cracked edges. These internally located cracked edges cannot, however, be polished and would therefore be unusable as coupling locations.